Module jdk.management
Package com.sun.management

Class VMOption


  • public class VMOption
extends Object
    Information about a VM option including its value and where the value came from which is referred as its origin.

    Each VM option has a default value. A VM option can be set at VM creation time typically as a command line argument to the launcher or an argument passed to the VM created using the JNI invocation interface. In addition, a VM option may be set via an environment variable or a configuration file. A VM option can also be set dynamically via a management interface after the VM was started. A VMOption contains the value of a VM option and the origin of that value at the time this VMOption object was constructed. The value of the VM option may be changed after the VMOption object was constructed,

    Since:
    1.6

    • Constructor Detail

      • VMOption

        public VMOption​(String name,
                String value,
                boolean writeable,
                VMOption.Origin origin)
        Constructs a VMOption.
        Parameters:
        name - Name of a VM option.
        value - Value of a VM option.
        writeable - true if a VM option can be set dynamically, or false otherwise.
        origin - where the value of a VM option came from.
        Throws:
        NullPointerException - if the name or value is null

    • Method Detail

      • getName

        public String getName​()
        Returns the name of this VM option.
        Returns:
        the name of this VM option.

      • getValue

        public String getValue​()
        Returns the value of this VM option at the time when this VMOption was created. The value could have been changed.
        Returns:
        the value of the VM option at the time when this VMOption was created.

      • getOrigin

        public VMOption.Origin getOrigin​()
        Returns the origin of the value of this VM option. That is, where the value of this VM option came from.
        Returns:
        where the value of this VM option came from.

      • isWriteable

        public boolean isWriteable​()
        Tests if this VM option is writeable. If this VM option is writeable, it can be set by the HotSpotDiagnosticMXBean.setVMOption method.
        Returns:
        true if this VM option is writeable; false otherwise.

      • toString

        public String toString​()
        Description copied from class: Object
        Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

        The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of: 

         getClass().getName() + '@' + Integer.toHexString(hashCode())
        Overrides:
        toString in class Object
        Returns:
        a string representation of the object.

      • from

        public static VMOption from​(CompositeData cd)
        Returns a VMOption object represented by the given CompositeData. The given CompositeData must contain the following attributes:
        description
        Attribute Name Type
        name java.lang.String
        value java.lang.String
        origin java.lang.String
        writeable java.lang.Boolean
        Parameters:
        cd - CompositeData representing a VMOption
        Returns:
        a VMOption object represented by cd if cd is not null; null otherwise.
        Throws:
        IllegalArgumentException - if cd does not represent a VMOption with the attributes described above.